| /* |
| * IPVS: Least-Connection Scheduling module |
| * |
| * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| * |
| * Changes: |
| * Wensong Zhang : added the ip_vs_lc_update_svc |
| * Wensong Zhang : added any dest with weight=0 is quiesced |
| * |
| */ |
| |
| #define KMSG_COMPONENT "IPVS" |
| #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| |
| #include <net/ip_vs.h> |
| |
| |
| static inline unsigned int |
| ip_vs_lc_dest_overhead(struct ip_vs_dest *dest) |
| { |
| /* |
| * We think the overhead of processing active connections is 256 |
| * times higher than that of inactive connections in average. (This |
| * 256 times might not be accurate, we will change it later) We |
| * use the following formula to estimate the overhead now: |
| * dest->activeconns*256 + dest->inactconns |
| */ |
| return (atomic_read(&dest->activeconns) << 8) + |
| atomic_read(&dest->inactconns); |
| } |
| |
| |
| /* |
| * Least Connection scheduling |
| */ |
| static struct ip_vs_dest * |
| ip_vs_lc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) |
| { |
| struct ip_vs_dest *dest, *least = NULL; |
| unsigned int loh = 0, doh; |
| |
| IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); |
| |
| /* |
| * Simply select the server with the least number of |
| * (activeconns<<5) + inactconns |
| * Except whose weight is equal to zero. |
| * If the weight is equal to zero, it means that the server is |
| * quiesced, the existing connections to the server still get |
| * served, but no new connection is assigned to the server. |
| */ |
| |
| list_for_each_entry(dest, &svc->destinations, n_list) { |
| if ((dest->flags & IP_VS_DEST_F_OVERLOAD) || |
| atomic_read(&dest->weight) == 0) |
| continue; |
| doh = ip_vs_lc_dest_overhead(dest); |
| if (!least || doh < loh) { |
| least = dest; |
| loh = doh; |
| } |
| } |
| |
| if (!least) |
| IP_VS_ERR_RL("LC: no destination available\n"); |
| else |
| IP_VS_DBG_BUF(6, "LC: server %s:%u activeconns %d " |
| "inactconns %d\n", |
| IP_VS_DBG_ADDR(svc->af, &least->addr), |
| ntohs(least->port), |
| atomic_read(&least->activeconns), |
| atomic_read(&least->inactconns)); |
| |
| return least; |
| } |
| |
| |
| static struct ip_vs_scheduler ip_vs_lc_scheduler = { |
| .name = "lc", |
| .refcnt = ATOMIC_INIT(0), |
| .module = THIS_MODULE, |
| .n_list = LIST_HEAD_INIT(ip_vs_lc_scheduler.n_list), |
| .schedule = ip_vs_lc_schedule, |
| }; |
| |
| |
| static int __init ip_vs_lc_init(void) |
| { |
| return register_ip_vs_scheduler(&ip_vs_lc_scheduler) ; |
| } |
| |
| static void __exit ip_vs_lc_cleanup(void) |
| { |
| unregister_ip_vs_scheduler(&ip_vs_lc_scheduler); |
| } |
| |
| module_init(ip_vs_lc_init); |
| module_exit(ip_vs_lc_cleanup); |
| MODULE_LICENSE("GPL"); |